The purpose of this Mentored Clinical Scientist Development Award (MCSDA) proposal is to provide the applicant with the adequate instruction and training needed to develop into a successful independent investigator in the field of biomedical optics. The proposed research and accompanying career development plan focuses on the biophysical changes in cartilage during laser mediated reshaping, and the development of non-invasive optical and thermal techniques to optimize clinical efficacy and safety. During laser irradiation, mechanically deformed cartilage undergoes a temperature dependent phase transformation which results in accelerated stress relaxation. Clinically, reshaped cartilage tissue can be used to recreate the underlying cartilaginous framework of structures in the head and neck such as the ear, nose, larynx, and trachea. The principal advantages of using laser radiation are precise control of both the space- time temperature distribution and time-dependent thermal denaturation kinetics. In order to optimize the reshaping process (thermally mediated stress relaxation), the thermo-optical response of cartilage tissue to laser irradiation and the phase transformation accompanying the reshaping process will be examined and mathematically modeled and correlated with chondrocytes viability. The thermo-optical and phase transformation models will be used to design a feedback-control system for safe cartilage reshaping, and tested in-vivo using a rabbit nasal septal cartilage. The proposal and accompanying career development plan address the three fundamental processes of laser-tissue interactions: 1) light propagation; 2) heat transfer; and 3) phase transformations (structural modification). Over the proposed five year training period, the applicant will acquire the requisite advanced engineering and mathematical techniques and physical methods necessary to study these biophysical processes. The applicant will also develop expertise in the field of laser-tissue interactions via the proposed career development plan structured around: 1) formal course instruction; 2) didactic sessions with faculty in physics, electrical engineering, and biophysics; and 3) attendance at weekly group meetings/departmental seminars at the Beckman Laser Institute and Medical Clinic at the University of California, Irvine. The applicant is a board-certified head and neck surgeon and engineer with an extensive research background in biomedical optics spanning all phases of his academic and clinical training. The MCSDA will provide the applicant with the fundamental skills needed to become an independent investigator in biomedical optics, and allow further development as a basic scientist.